Field of the Invention
Embodiments of the present invention relate to control systems for irrigation systems. More particularly, embodiments of the present invention relate to control systems to guide irrigation systems with elevated irrigation pipelines in an automated and continued manner while reconfiguring alignment of the pipelines in various configurations.
Description of the Related Art
Crops are cultivated throughout the world in a wide variety of climates with different terrains and soils. It is desirable in many of these climates to artificially supplement the climate's natural precipitation via irrigation systems to ensure crops receive adequate water. Additionally, irrigation systems can be used to deliver fertilizers and chemicals to, among other things, promote healthy crop growth, suppress weeds, and protect crops from frost.
Common irrigation systems include center-pivot systems and lateral-move systems, each having an elevated, elongated pipe supported by a plurality of drive towers spaced along the pipe. The pipe includes a plurality of spaced sprinklers that may extend downward toward the crops to enable distribution of water to the crops from above. Center-pivot systems are ideal for use in fields having circular crop areas and generally include a hydrant located in the middle of each circular crop area. In such systems, a plurality of spans are linked together radially outward from the hydrant. Each span includes a tower and a truss assembly that supports the pipe and the sprinklers which deliver water to the crop area while the spans rotate about the hydrant. Lateral-move systems are ideal for use in square, rectangular, and irregular-shaped fields. Such systems generally include one or more hydrants located in and/or adjacent to a field and/or one or more ditches located along or through a field that are connected to the pipe and the sprinklers. Unlike the center-pivot system having a pipe with a stationary end, the pipe in a lateral-move system is connected to and extends from a movable cart designed to traverse up and down a cart path. The pipe may be locked at an angle perpendicular to the cart path and pivot at an end at the cart path, which is desirable if the cart path extends down the middle of a field to enable pivoting from one side of the cart path to the other with each pass along the cart path.
In both center-pivot and lateral move systems, each span is long, for example, one hundred thirty five feet and two hundred feet. To move the span during an irrigation operation, each of the drive towers includes two or more wheels that are fixed in orientation and driven by a mechanical drive unit. The mechanical drive units may be a series of electric motors or other similar sources of propulsion. In general, the mechanical drive units propel the span forward or backward in a circular or lateral pattern along a field and over crops, to provide crop irrigation.
While the spans are being driven, it may be desirable to automatically reconfigure an alignment of the irrigation system. For instance, it may be desirable to reconfigure the alignment of one or more spans to relieve stress in the pipe caused by an uneven grade or to cause one or more spans to wrap or swing around obstacles in a path of the system.